Cloned for documentation impact, refer to Bug # 893379 for implementation details.
Response from Nikola: Hey Martin, It seem that you are looking at the wrong blueprint as it was superseded by https://blueprints.launchpad.net/nova/+spec/improve-block-device-handling (see the URL field in the bug - it was updated by my colleague Xavier alongside comment #7) Make sure to click on the 'read the full specification' link on that page and check out the wiki with more details about it (hint: https://wiki.openstack.org/wiki/BlockDeviceConfig) Let me know if you need more info. N.
No tech review received from Nikola. Approved and merged this change as it includes only a new config file and options.